A while back, I bought a a hardcover book that has a selection of MAD Magazine work by Sergio Aragones. They got Patrick McDonnell to do the foreword for it, which is an interesting read.

"Sergio Aragones is one of our Zen masters of cartooning. He lives in the moment. He breathes. He sits. He drinks a cup of coffee. He draws a crowd scene with 200 individual characters doing 200 individual funny gags." (an excerpt from the foreword)

Patrick even did a drawing, a nice tribute to 'El Maestro' (how some people call Sergio). It's his take on one of Sergio's recurring MAD features, "The Shadow Knows", where Mooch casts a shadow that looks suspiciously like Sergio himself .